Middle-aged men with unexplained anemia may be caused by malnutrition, chronic peptic ulcer, hemorrhoids and other reasons. 1. Malnutrition: If middle-aged men have insufficient nutritional intake for a long period of time, it may easily lead to iron, folic acid and vitamin B12 deficiencies, thus causing anemia. However, the cause may not be detected in the early stage and the symptoms are not obvious. 2. Chronic peptic ulcers: such as bleeding caused by chronic gastric ulcers, if the amount of bleeding is small, the patient does not have any symptoms in the early stage, and it is easy to show anemia over time. 3. Hemorrhoids: more common in middle-aged men, easy to cut the vascular mass when stool, triggering bleeding in the stool, long time not get rooted out, will also cause chronic anemia. In addition to the above, varicose veins at the base of the stomach, duodenal ulcer, blood system diseases are also prone to cause anemia in middle-aged men. It is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.